JPH01130054A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To accelerate fuel atomization as well as to improve combustibility by forming each inner wall surface of plural pieces of flow dividing holes formed as opposed to a fuel injection nozzle, into surface roughness coarser than 5mum. CONSTITUTION:When a needle valve 113 is opened, fuel is discharged out of a nozzle 112 and separated in two directions by flow dividing holes 141, 142, then it is sprayed out of a fuel injection valve 100. Each of these flow dividing holes has a circular section of about 0.8mm in a radius of curvature, and each inner wall surface is processed into matte finish by means of shot blasting or the like, and the surface is coarser then 5mum. Consequently, a fuel flow in these flow dividing holes 141, 142 is disordered, whereby fuel grain size becomes smaller. Since the fuel grain size is minimized when a radius of curvature on an inner wall surface of the flow dividing hole is 0.8mm, such fuel atomization that is small in the grain size is fed to the inside of a combustion chamber. With this constitution, combustion is improved and transient responsiveness in an engine is improved and, what is more, fuel consumption is substantially enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection valve that separates fuel discharged from an injection hole into a plurality of directions using a flow dividing hole and injects the fuel.

[Prior Art] For example, in an engine having two intake valves for one cylinder, such as a three-valve or four-valve engine, an intake passage connected to one cylinder branches into two in the middle, and each cylinder has two intake valves. Connects to the intake boat. The fuel injection valve is provided upstream of a branch of the intake passage and injects fuel toward the branch. Therefore, in order to prevent the fuel from adhering to the wall of the intake passage, an adapter with two flow dividing holes is fitted to the tip of the fuel injection valve, and the fuel spray flow is separated into two by these flow dividing holes. It is preferable to supply the air to each intake boat, and this is achieved by the configuration disclosed in Japanese Utility Model Application Publication No. 62-105363 or Nippon Denso Technical Report No. 31-223.

[Problems to be Solved by the Invention] However, although the conventional fuel injection valve described above can separate the fuel into two directions, the atomization of the fuel is not sufficient, and as a result, the transient response of the combustion and engine is poor. It hasn't been improved enough.

An object of the present invention is to obtain a fuel injection valve that can separate fuel in multiple directions and sufficiently promote atomization of the fuel.

[Means for Solving the Problems] The fuel injection valve according to the present invention is characterized in that the inner wall surface of the flow dividing hole has a surface roughness rougher than 5 μm.

〔Example] The present invention will be explained below based on illustrated embodiments.

FIG. 2 shows a fuel injection valve 100 to which the present invention is applied. In this figure, an injection hole 112 is formed in the lower end of a nozzle body 111, and a needle valve 113 for opening and closing the injection hole 112 is housed inside the nozzle body 111 so as to be able to move up and down. An annular plate 114 is provided above the nozzle body 111, and the nozzle body 111 is fitted into the lower end opening 116 of the casing 115 together with the annular plate 114.

On the other hand, the inlet member 121 connected to a fuel supply line (not shown) is fitted into the upper end opening 117 of the casing 115 at its flange portion 121a, and the pipe portion 121b extending below the flange portion 121a is It forms an iron core located at the center of a solenoid coil 131, which will be described later. A fuel passage 123 is formed in a pipe member 122 fixed to the axial center of the inlet member 121.
A filter 124 is provided at the connection portion with the supply line 21. The fuel passage 123 and the throttle hole 112 are connected by a passage formed inside the casing 115 and the nozzle body 111.
The fuel flowing through the fuel injection hole 3 is discharged from the injection hole 112 when the needle valve 113 is opened. This discharged fuel is divided into two directions by flow dividing holes 141 and 14.2, which will be described later, and is injected from the fuel injection valve 100.

An annular movable core 125 is fitted into the head of the needle valve 113, and a spring 126 is provided between the movable core 125 and the pipe member 122. This spring 126 is connected to the movable core 12
5, the needle valve 113 is always biased downwardly through the nozzle body 1.
11 and closes the injection hole 112. The needle valve 113 is opened by energizing the solenoid coil 131. That is, the movable core 125 is made of a magnetic material, and is attracted upward by energizing the solenoid coil 131, thereby causing the needle valve 113 to separate from the seat portion 127 and open the injection hole 112. At this time, the raised position of the needle valve 113 is regulated by a stopper 118 formed approximately at the center of the needle valve 113 interfering with the annular plate 114. When the power supply to the solenoid coil 131 is cut off, the needle valve 113 is lowered by the elastic force of the spring 126 and closes the injection hole 112.

Power supply control to the solenoid coil 131 is performed by an electronic control circuit (not shown), and the electronic control circuit applies voltage pulses to the solenoid coil 13 according to the operating state of the engine.
Supply to 1. Electronic control circuit and solenoid coil 131
A power supply connector 132 is fixed to the upper end of the casing 115 in order to electrically connect the
The connector pin 133 provided in the solenoid coil 1
31.

FIG. 3 shows an enlarged view of the lower end of the fuel injection valve lOO. The sleeve 140 is press-fitted and fixed to the lower end of the nozzle body 111, and the sleeve 140 is provided with two flow dividing holes 141 and 142 formed opposite to the injection hole 112. The flow dividing holes 141, 142 have a circular cross section as shown in FIG. 1(b). A bottle 119 formed at the lower end of the needle valve 113 extends through the injection hole 112 and is located in a chamber 143 formed in the sleeve 140 above the flow diverter hole 141 , 142 .

FIGS. 1(a) and 1(b) show the sleeve 1 in the first embodiment.
40 is shown enlarged. Each of the branch holes 141 and 142 is narrow on the downstream side, and is inclined outward with respect to the center line of the adapter 140 so as to be spaced apart from each other as it goes downstream. The inner wall surfaces of the flow dividing holes 141 and 142 are processed into a satin-like texture using shotplast or the like, and the surface roughness thereof is rougher than 5 μm. Further, the flow dividing hole 14L142 has a circular cross section, and the radius of curvature R0 of the inner wall surface is set to about 0.8 mm.

By setting the surface roughness of the flow dividing holes 141, 142 to 5 μm or more in this manner, the fuel flow within the flow dividing holes 141, 142 is disturbed, the splitting of the liquid film of the fuel is promoted, and the fuel particle size is reduced. Therefore, the fuel flows through the branch holes 141 and 14.
2, the fuel is not only injected separately in two directions, but also well atomized, and fuel spray with small particle size is supplied into the combustion chamber of the engine. This improves combustion, improves engine transient response, improves fuel economy, and reduces emissions. Note that if the fuel contains foreign matter, this foreign matter will be removed from the flow dividing hole 141.
Even if the fuel enters the recess on the inner wall surface of 142, since the fuel always flows along the inner wall surface, it is immediately washed away and does not adhere to the inner wall surface.

FIG. 4 shows the relationship between the surface roughness of the inner wall surfaces of the flow dividing holes 141 and 142 and the Sauter average particle size of fuel. As can be understood from this figure, the particle size of the fuel becomes smaller as the surface roughness of the inner wall of the flow dividing hole increases, and becomes a significantly smaller value when the surface roughness is 5 μm or less and remains almost constant. However, in the first embodiment, the surface roughness of the inner wall surfaces of the flow dividing holes 141 and 142 is set to be 5 μm or more.

FIG. 5 shows the radius of curvature R0 of the inner wall surface of the flow dividing hole 141142.
and the Sauter average particle size of the fuel. As can be understood from this figure, the particle size of the fuel decreases as the radius of curvature R0 increases, and the radius of curvature R0 becomes 0.8
When it exceeds mm, it takes a nearly constant value. The radius of curvature R0 is determined to be approximately 0.8 mm in the first embodiment. In this way, the larger the radius of curvature R0 of the inner wall surface of the flow dividing holes 141 and 142, the smaller the particle size of the fuel becomes.
．． This is because the contact area between the fuel and the inner wall surface in the inner wall 142 becomes larger, which thins the liquid film of the fuel flow and promotes atomization of the fuel.

FIG. 6 shows an enlarged view of the adapter 140 in the second embodiment. In this embodiment, the diameter of the inner wall surface of the flow dividing holes 141, 142 decreases stepwise toward the downstream side, that is, step-like unevenness is formed on the inner wall surface. The surface roughness of this inner wall surface is also 5 μm or more. Therefore, this second embodiment also provides the same effects as the first embodiment. In addition, the adapter 140 in this embodiment
can be molded from synthetic resin, keeping costs low.

FIGS. 7(a) and 7(b) show an adapter 140 of a third embodiment. This third embodiment is different from the first embodiment shown in FIGS. 1(a) and 1(b) in that the inner wall surfaces of the flow dividing holes 141 and 142 have arcuate portions 141a and 142a close to each other. The difference is that it has a semicircular cross section, but the other configurations are the same. Also in this embodiment, the flow dividing holes 141, 14
The inner wall surface of No. 2 has a surface roughness of 5 μm or more, and the radius of curvature R0 of the arc-shaped portion of the inner wall surface is 0.8 mm or more,
The same effects as in each of the above embodiments can be obtained.

FIGS. 8(a) and 8(b) show an adapter 140 of a fourth embodiment. In this fourth embodiment, the inner wall surface of the flow dividing hole 14L142 has a semicircular cross section, but unlike the third embodiment,
The straight parts are opposed to each other. Further, the surface roughness of the inner wall surfaces of the flow dividing holes 141 and 142 is 5 μm or more.

FIGS. 9(a) and 9(b) show a fifth embodiment. In this embodiment, the inner wall surfaces of the flow dividers 141 and 142 have a rectangular cross section, and the other grooves are similar to those in the above embodiments.

FIG. 10 shows a sixth embodiment. The bottle 119 has a conical surface that expands downward, and the conical angle is θ. Then, the fuel discharged from the injection hole 112 flows along the outer peripheral surface of the bottle 119 and has a cone angle θ on the downstream side of the bottle 119. is sprayed at a spray angle θ smaller than . This fuel flows through the separation wall 144 formed between the branch holes 141 and 142.
and is injected from branch holes 141 and 142. Letting θ be the angle formed by the straight line connecting the outer edge of the conical portion located at the tip of the bottle 119 and each outer edge of the flow dividing holes 141 and 142, θ1≧θ. Therefore, the fuel does not come into contact with the inner wall surfaces located outside of the flow dividing holes 141 and 142, but comes into contact with the wall surface of the separation wall 144 and is injected. The surface roughness of the wall surface of the separation wall 144 is set to 5 μm or more, thereby promoting atomization of the fuel. Note that the adapter 140
The number of flow dividing holes formed may be three or more.

〔Effect of the invention〕

As described above, according to the present invention, fuel can be separated and injected in multiple directions, and atomization of the fuel can be sufficiently promoted. Combustion is therefore improved, engine transient response is improved, fuel economy is improved and emissions are reduced.

[Brief explanation of the drawing]

FIG. 1(a) is a sectional view showing the adapter of the first embodiment, FIG. 1(b) is a plan view of the adapter of FIG. 1(a), and FIG. 2 is a fuel to which the embodiment of the present invention is applied. Figure 3 is an enlarged cross-sectional view of the main parts of the fuel injection valve shown in Figure 2. Figure 4 shows the relationship between the surface roughness of the inner wall of the flow dividing hole and the Sauda average particle size of the fuel. FIG. 5 is a graph showing the relationship between the radius of curvature of the inner wall surface of the flow dividing hole and the Sauter average particle diameter of the fuel. FIG. 6 is a sectional view showing the adapter of the second embodiment, and FIG. a) is a sectional view showing the adapter of the third embodiment; FIG. 7(b) is a plan view of the adapter of FIG. 7(a); FIG. 8(a) is a sectional view showing the adapter of the fourth embodiment. , FIG. 8(b) is a plan view of the adapter of FIG. 8(a), FIG. 9(a) is a sectional view showing the adapter of the fifth embodiment, and FIG. 9(b) is a plan view of the adapter of FIG. 8(a). FIG. 10 is a sectional view showing the adapter of the sixth embodiment. 100...Fuel injection valve, 112...Injection hole, 141.142...Diversion hole.

Claims (4)

[Claims] 1. In a fuel injection valve that separates and injects fuel discharged from an injection hole in multiple directions by a plurality of dividing holes provided opposite to the injection hole, the inner wall surface of the dividing hole has a surface roughness of less than 5 μm. A fuel injection valve comprising: 2. 2. The fuel injection valve according to claim 1, wherein the inner wall surface of the flow dividing hole has a circular cross section, and the radius of curvature of the circle is 0.8 mm or more. 3. Claims characterized in that the inner wall surface of the flow dividing hole has a semicircular cross section with arcuate portions close to each other, and the radius of curvature of the arcuate portion is 0.8 mm or more. The fuel injection valve according to item 1. 4. 2. The fuel injection valve according to claim 1, wherein the inner wall surface of the flow dividing hole has a rectangular cross section.